In the field of blood treatment, hemodialysis is the most widely used technique, although other techniques are also available such as plasmapheresis, hemoperfusion, blood oxygenation, and techniques for passing blood through blood treatment media such as an absorptive agent for the removal of toxins or the like. Typically, an arterial blood set delivers blood from the patient to the hemodialyzer or other desired blood treatment unit. After the blood has passed through the hemodialyzer, it is conveyed through a venous blood set back to the patient.
The arterial and venous blood sets typically each have about two meters of tubing, extending from patient connectors to other set components such as bubble removal chambers, a length of roller pump tubing or another pump device fitment, branch connection sites, a pressure pillow, and the like. Also, typically another meter of tubing extends between these various other set components and the dialyzer or other blood treatment device. Numerous other known devices may also be positioned on the blood sets, such as filters.
In the early days of dialysis, blood lines and dialyzers were hand-assembled before dialysis, and then disassembled, piece-by-piece, after dialysis for cleaning and resterilization. These early dialyzers were of the plate dialyzer form, and, generally, everything was reused except for the dialyzing membranes. Typically, glass chambers and various metallic fittings were press fit into latex blood tubing, with these components being reused a large number of times.
Since such a process was very expensive in terms of labor cost and time consumption, plastic, pre-sterilized dialyzers and blood lines were introduced in the late 1960""s. Initially, these items were disposed of after a single use. However, in due course, the dialyzers particularly began to be reused, always on the same patient and typically for only four to six uses. In countries with less government funding and/or lower cost of labor the reuse of dialyzers, bloodlines, and even fistula needles has been and still is common, despite safety issues.
When U.S. government funding of dialysis began in the mid 1970""s, dialyzer reuse substantially disappeared. However, since another funding change in 1982, U.S. dialyzer reuse has been once again increasing.
Particularly, hollow fiber dialyzers have been reused, especially since the introduction of non-cellulosic membranes such as polysulphone, which are more capable of exposure to oxidizing agents such as more concentrated liquid bleach, so that at the present time most hemodialyzers are reused, with the reuse typically being done with semi-automated equipment that controls the rinsing, bleach and antiseptic solution application, and other aspects of the disinfection process. Typically, in the more recent reuse techniques, the dialyzer is first disconnected from the arterial and venous blood sets, which are thrown away. Hollow fiber dialyzers have their headers removed in some cases so that the fiber manifolds can be swabbed and cleaned. Then, the dialyzers are connected by short reuse tubes which join its blood inlet, outlet, and dialysate ports to the respective ports on the reuse equipment. The blood and dialysate pathways are sequentially rinsed, followed by application of a bleach solution and another water rinse, following which the dialyzer is filled with a disinfectant solution. The dialyzer is then separated from the short reuse connecting tubes capped, and then stored until the patient""s next dialysis. Dialyses are typically performed on a patient three times a week.
Immediately prior to the next use, the dialyzer is typically connected to a new arterial set that has been previously primed with sterile, physiological saline. Then a venous set is attached. The system is rinsed with sterile physiologic saline solution for essential elimination of the disinfectant.
Commonly, blood lines of the arterial and venous sets have not been reused, partly because the cost of blood lines is less than the cost of dialyzers, and also because blood lines are more difficult to reuse than dialyzers. This is because, contrary to the typical hollow fiber dialyzers, traditional blood lines have numerous branch lines, dead end spaces, and enlarged spaces such as are found in the bubble removal chambers and pressure pillows. Thus, efficient, effective cleaning of traditional arterial and venous sets is difficult or impossible.
Also, conventional arterial and venous sets are more difficult to set up for dialysis reuse than typical hollow fiber dialyzers, since the above mentioned components also cause difficulties in the removal of the chemical sterilant prior to reuse. The presence of filters, as are commonly found in the venous sets, presents a major obstacle to effective cleaning prior to reuse. Likewise, arterial and venous sets tend to be long and cumbersome after they have been unwound, making it difficult to manipulate the set during reuse, storage, and setup.
Additionally, unlike dialyzers, certain components of the prior art blood lines are subjected to repeated mechanical force which, as they are made from materials which degrade with use, and thus are not ideal for reuse. This also raises safety issues. For example, the roller pump tubing segment typically carried by blood sets can quickly suffer from a deterioration in elasticity, since the pump segment tubing is crushed and reexpanded thousands of times by the action of the roller pump. The functioning of the pump segment tubing depends upon its elastic xe2x80x9cspring backxe2x80x9d capability. With a loss of some of that characteristic to spring back from the crushing provided by the roller pump, the amount of blood pumped per rotation of the roller pump rotor decreases. To make matters worse, this can go unnoticed as blood flow rates are typically calculated indirectly in the blood pump by a measurement of the rotational speed of the pump rotor, so that the flow rate may decrease even though the pump rotor speed is maintained. This can take place in part because plasticizers of the typically PVC roller pump segment may have leached out or otherwise because of characteristics of the materials used.
Also, a worn pump segment or diaphragm may shed into the pumped blood excessive amounts of particles from the plastic of which the segment is made.
Also, blood filters and transducer protector filters are reused only with difficulty and inefficiency, because the blood tends to clog the openings of the respective filters. Likewise injection sites may quickly wear out due to repeated punctures and the loss of elasticity as a consequence of use in a dialysis procedure. Organic material that collects in the puncture sites of elastomeric injection site partitions is especially difficult to remove and decontaminate.
Currently, arterial and venous sets for dialysis are reused in some clinics. However, in such reused sets the arterial blood line is generally not equipped with an arterial chamber, which prevents accurate monitoring of arterial pre-pump or post-pump pressures, raising a significant safety issue. Likewise, venous blood lines that are reused generally do not include a filter, which raises another significant safety issue. Furthermore, the reusable arterial and venous blood lines generally lack injection sites and other branch lines, which creates a significant inconvenience and a safety issue.
The reason for these deficiencies in the above reusable blood lines lies in the difficulty of reusing blood lines which have chambers, filters, injection sites, dead end side ports, and branch lines.
Luther et al. U.S. Pat. No. 4,612,170 discloses a blood oxygenator which has a removable and reusable heat exchanger. The remainder of the oxygenator and the blood lines are apparently not intended not to be reused.
Also, the Medisystems Corporation offered for sale during the 1970""s and 1980""s a neonatal venous line for dialysis in which a central chamber with filter was removably connected at both ends to lengths of tubing which each carried a branching connector site. The purpose of this was to permit replacement of the filter in case the filter became severely clotted during dialysis, to which neonatal dialysis is sometimes prone. It is not believed that any suggestion was made about reuse of any of the components of the neonatal venous line.
By this invention, a blood treatment method is provided, which is typically a hemodialysis technique but may comprise other blood treatment methods as well. The method comprises the following steps:
One flows blood sequentially through connected members which comprise a first conduit; a first blood handling member comprising at least one of a first debubbling chamber and a pump device fitment; a second conduit; a blood treatment device such as a membrane dialyzer; a third conduit; a second blood handling member comprising at least one of a second debubbling chamber and pump device fitment; and a fourth conduit. In a preferred embodiment, the blood treatment device is a hemodialyzer. Typically, blood is withdrawn from the patient into the first conduit, and returned to the patient through the fourth conduit. The conduits are typically flexible plastic tubes of the arterial and venous blood sets, although rigid materials and/or non-tubular shaped conduits can preferably be employed in certain circumstance such as cassetted devices or conduits that are permanent or semi-permanent. Attachments to the treatment device or monitoring/supply device. Following such treatment, one terminates the flowing of blood and substantially removes the blood from the above components.
In accordance with this invention, at least one of the first and second blood handling members is disconnected from the respective flexible tubes and removed. One then connects ends of at least one of the first and second conduits and/or the third and fourth conduits together, to recreate a blood flow path with the absence of at least one the first and second blood handling members. At least one of the first and fourth conduits are then connected at a free end to a source of cleaning/storage solution, which may sequentially or otherwise include water for rinsing, bleach, and a disinfecting solution used for storage of the blood lines, either with the blood lines being connected to the blood treatment device (hemodialyzer) or separate therefrom if desired. One then flows the cleaning/storage solution through the first through fourth conduits and, optionally, the blood treatment device which in that circumstance is not disconnected from the tubes.
Prior to such connection, the ends of the first, second, third and fourth conduits are preferably treated with an antimicrobial agent such as liquid bleach, following which, the first and second, and the third and fourth, conduits may be connected, thus reducing the risk of microbial contamination.
It is preferred that the above blood treatment method is performed a plurality of times, for example a dozen or more times, with at least some of the same first through fourth conduits. This can save 65 percent or more of conventional, fully disposable plastic of the blood line sets (by weight) in each dialysis procedure, since the first through the fourth conduits may comprise the longest portions of the respective arterial and venous sets. Such a reuse, if universally used in all current United States dialysis procedures, could reduce the consumption of plastic up to four million kilograms per year, which must now be both paid for and then disposed of as biologically hazardous material.
It should also be added that, particularly in the situation where the blood lines remain connected to the dialyzer during cleaning and storage for reuse, the reuse of the first through fourth conduits can be accomplished at an extremely low increased cost compared to the reuse of the membrane dialyzer by itself. The reuse cycle with a conventional reuse machine can be practically the same whether the dialyzer is connected to the reuse equipment alone, or with attached long tube assemblies comprising the first through fourth conduits. Preferably, these long conduit assemblies are free of branch lines, dead end spaces associated with branch lines and other components, and other features that inhibit their reuse.
If desired, either or both of the second and third conduits may be permanently connected to the dialyzer.
Also, the performance standards of the first through fourth conduits on reuse can remain high through a dozen reuses or more, providing performance that is substantially equivalent to the original equipment specifications. It is generally preferred, to enhance reuse capability, that the first, second, third, and fourth (first through fourth) conduits are tubes made of a plastic which is substantially free of plasticizers, or at least leachable plasticizers. For example, polyurethane, silicone, polycarbonate and similar materials may be used. Also, thermoplastic elastomer materials may be used such as Kraton, sold by The Shell Chemical Company.
Typically, with each reuse of the first through fourth conduits, new first and second blood handling members may be respectively connected between the first and second, and the third and fourth, conduits. Priming solution may be passed through the connected conduits blood handling members, and blood treatment device (dialyzer), followed by flowing blood sequentially therethrough in accordance with the original method described above.
Further in accordance with this invention, an arterial or venous set for blood handling is provided, usable in the above method. The set comprises of a first typically flexible tube having ends which respectively carry a first connector (typically a dialyzer connector) and a second connector. A central assembly comprises a pathway conduit having at least one of a blood degassing chamber, a connected branch tube, a pump device fitment, and an injection site. The central assembly carries a third connector which is connected with the second connector, and a fourth connector.
A second typically flexible tube is also provided to the set, having ends which respectively carry a fifth connector and a sixth connector (typically a patient access connector). The fifth connector is connected to the fourth connector of the central assembly. At least the second and fifth connectors are of the type which permit repeated connection and disconnection to permit repeated, sealed blood flow through the set while the connectors are connected, so that they may be reused time after time, while the central assembly may be replaced.
The first flexible tube may correspond exactly to the previously discussed second or third conduits. The second flexible tube may correspond exactly to the first or fourth conduits, depending on usage.
Also, it is preferred for at least the second connector and the fifth connector to define first sealing surfaces that respectively sealingly abut against other sealing surfaces of the third and fourth connectors, to which they are respectively connected. The second and fifth connectors also have second sealing surfaces, the latter two connectors being also connectable with each other to form a sealed connection by contact of the second sealing surfaces while the first sealing surfaces are positioned in exposed manner within the connected second and fifth connectors. This latter condition is accomplished after the central assembly has been removed, and the first and second tubes are connected together for cleaning and reuse. The second sealing surfaces form a sealed connection between the second and fifth connectors by sealing contact together, while the first sealing surfaces in this condition are positioned in exposed manner within the connected second and fifth connectors, so that antimicrobial solution in the joined first and second flexible tubes can be in contact with the first sealing surfaces. Thus, upon desired reuse of the first and second tubes, they may be connected again with the third and fourth connectors of a new central assembly under aseptic conditions since the first sealing surfaces have been cleaned and rendered aseptic.
The second and fifth connectors may each define a threaded sleeve of differing diameter compared with the other sleeve, to permit telescoping, threaded interengagement for a locking connection while the second sealing surfaces are in sealing abutment.
Also, the threaded sleeve of at least one of the second and fifth connectors may be threaded both inside and out to provide engagement between the second and fifth connectors, and also to alternatively provide engagement with the connectors of the central assembly.
Alternatively, an O-ring connector system may be used in which at least one O-ring comprises at least one first or second sealing surface.
Further in accordance with this invention, a flow through blood treatment device and a connected blood set portion comprises a housing, a blood inlet, a blood outlet, and at least one membrane in the housing. The housing defines a blood flow path between the blood inlet and outlet on one side of the membrane, and a second flow path defined on the other side of the membrane. The blood inlet and the blood outlet are each respectively connected to lengths of first blood flow tubing by first connectors positioned at one end of each of the respective lengths of first blood flow tubing, which connectors may provide permanent connection if desired.
The first blood flow tubing carries on its other end a second connector which is connected to a fifth connector (similar to that previously described) carried on one end of a second blood tube. Each length of the second blood tube is connected to a sixth connector, typically a patient access connector, on its end opposed to the end which carries the fifth connector. Thus, a blood treatment device such as a dialyzer may be connected to one or both of the arterial and venous blood sets, in which each of the inlet and outlet tubing assemblies comprises first and second lengths of tubing which are removable one from the other by disengagement of the respective connectors.
Such an arrangement may be cleaned and stored for reuse. Then, when reuse is desired, the respective lengths of first and second tubings can be disconnected, a central assembly containing, for example one or more blood degassing chambers and/or a blood pumping device such as roller pump tubing, may be connected between the respective first and second tubes so that the blood treatment device becomes ready for use.
The respective arterial and venous sixth connectors on the free ends of the second tubes may be connected to each other so that the flow path of the blood treatment device is formed into a closed loop, for storage purposes. Alternatively, the respective sixth connectors may be connected to opposed ends of a short shunt tube or an overconnector for the same purpose.
Particularly, the second and fifth connectors of the above device may have the design previously described, where the connectors define first and second sealing surfaces and where the second and fifth connectors are connectable with each other, with abutment together of the second sealing surfaces while the first sealing surfaces are positioned in exposed manner within the connectors, so that the first sealing surfaces may be cleaned and rendered aseptic for subsequent sealing contact with a sealing surface of another connector.
Because the long first through fourth tubes may be reused many times, they may be made of larger inner cross-sectional area at a very small cost increase, especially when factored over the many separate dialyses in which they are used. Larger inner cross-sectional areas, for example about 0.17 to 0.4 cm2, can desirably reduce the flow pressure drop, which is particularly of advantage in the higher flows of modern dialysis procedures.
Preferably, new first and second blood handling members may be incorporated into the blood treatment device which is to be reused after the antimicrobial agent has been completely removed from the system and replaced with normal saline solution. Thus, setup can be fast and efficient, because the greater part of the blood sets are already primed.